Spotting fluid for differential sticking

ABSTRACT

A new composition for a spotting fluid and a method of using such spotting fluid for freeing differential stuck pipe in a subterranean well drilling operation is disclosed. The composition comprises an invert water-in-oil emulsion comprising iso-butyl oleate as its external phase and glycerin as the internal phase. In an altemative embodiment, calcium chloride and water may be substituted for glycerin.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to compositions and methods for unstickingor freeing differential stuck pipe used in drilling a borehole forhydrocarbons in a subterranean formation.

[0003] 2. Description of Relevant Art

[0004] Rotary drilling methods employing a drill bit and drill stemshave long been used to drill wellbores in subterranean formation.Drilling fluids or muds are commonly circulated in the well during suchdrilling to cool and lubricate the drilling apparatus, lift cuttings outof the wellbore, and counterbalance the subterranean formation pressureencountered. The specific gravity of a well fluid is normally adjustedin such a way that the pressure of the fluid on the rock formationsexceeds the formation pressure on the well. As a result, liquidcomponents of the well fluid are forced into the formation surroundingthe well while insoluble components settle on the walls of the well inthe form of a stabilizing “filter cake.”

[0005] Inevitably in drilling a well, the path followed by the drillpipes will deviate some from the vertical or other desired path for thewell. At such consequent deviations or “kinks,” the rotating drill pipesmay come into contact with the filter cake and even with the wall of thewell and become buried therein, resulting in jamming or sticking.

[0006] Such jamming or sticking is particularly common when pipeconnections, which are larger in diameter than the drill pipesthemselves, come into contact with the kinks.

[0007] The most frequent cause of jamming or sticking of drill pipes isdifferential jamming. Differential jamming can occur when the rotationof the drill pipes is stopped. If a drill pipe then comes into contactwith the filter cake adhering to the wall of the well, the drill pipe isforced into the wall of the well by the hydrostatic pressure of thecolumn of mud. The contact surface is then isolated from the mudpressure. If, as is usually the case, the mud pressure is greater thanthe formation pressure, the contact surface is held fast to the wall bysuction forces. The suction force increases with the thickness andcompressibility of the filter cake. With time, even relatively largesections of the drill pipe can become held fast. Thus, prompt treatmentis best.

[0008] Prompt freeing of the stuck drill pipe is also needed toalleviate lost drilling time and the consequent costs which thatinvolves.

[0009] Spotting fluids are used by those skilled in the art to freestuck drill pipe. Spotting fluids need a good lubricating effect and theability to ensure good oil wettability of the surfaces of the drill pipeand of the walls of wells coming into contact with the drill pipe.

[0010] To maximize utility in freeing stuck pipe, the spotting fluidshould be applied at exactly the point in the well at which the pipe hasbecome stuck. This is accomplished in the same general way in which thewell fluid is introduced into the well. Instead of the well fluid, thespotting fluid is forced through the interior of the drill pipe to thebit, which leaves the bit, and slowly ascends in the well to the pointof the stuck pipe. Thus, it is critically important to be able toexactly adjust the specific gravity of the spotting fluid so that itwill be such as to keep the spotting fluid at that location in the wellof the stuck pipe for sufficient time for its lubricity-enhancingproperties to act to free the stuck pipe.

[0011] Since prompt use of a spotting fluid is important, it is standardpractice at the drill site to store spotting fluid or spotting fluidconcentrates which may rapidly be adjusted to the required density andconsistency by addition of barite or other weighting materials andoptionally other additives and water.

[0012] Spotting fluids known in the art typically consist of hydrocarbonmixtures, often based on diesel oils or mineral oils. Emulsifiers andsurfactants are typical additives.

[0013] Such prior art spotting fluids may cause environmental concernsif they come into contact with ground soil formations. Further, sinceoil based spotting fluids mix with the drilling fluid during dischargefrom the well, such oil based spotting fluids contaminate the waterbased drilling fluids which then have to be discarded and separatelytreated to avoid environmental concerns., adding further to the drillingcosts. The environmental concerns are enhanced in off-shore drillingwhere there is less space to store discarded fluids for treatment.

[0014] U.S. Pat. No. 4,964,614 issued in 1990 to Mueller et al.discloses an ester based spotting fluid that is said to have fewerenvironmental concerns than the mineral oil or diesel oil based fluids.However, a need continues to exist for more efficient and improved,environmentally friendly spotting fluids that are effective in freeingstuck pipe.

SUMMARY OF THE INVENTION

[0015] The composition and method of the present invention are useful intreating and alleviating stuck pipe, particularly differential stuckpipe, during drilling of a wellbore in a subterranean formation. Thepreferred composition of the invention is an invert oil mud systemcomprising iso-butyl oleate as the external phase and glycerin(preferably) or calcium chloride (CaCl₂) solution as the internal phase.For application to stuck pipe downhole, this emulsion may be combinedwith, added to, or mixed with other fluids for carrying the emulsion tothe treatment site and holding it there long enough to free the stuckpipe.

DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention provides a new composition and method ofusing such composition for freeing stuck drill pipes. The compositionand method are particularly useful in freeing differential stuck pipe.

[0017] The composition of the invention comprises a water-in-oilemulsion or an invert oil mud system. The emulsion comprises iso-butyloleate as the external phase and either glycerin (preferably) or calciumchloride as the internal phase, preferably in a ratio ranging from about95:5 to about 50:50 oil phase to water phase or more specifically oleateto either glycerin or about 38% aqueous calcium chloride solution. Thisemulsion may be added to or mixed with other treatment products and withmaterials or products to facilitate delivery of the emulsion to the siteof the stuck pipe and holding of the emulsion at such site sufficienttime to enable the emulsion to cause or effect unsticking of the pipe.Such typical additives or additional materials include, for example,about 2 to about 14 pounds per barrel EZ-MUL NTE™ (an emulsifier/oilwetting agent), available from Halliburton Energy Services, Inc.,Houston, Tex.; about 0.5 to about 3.0 pounds per barrel DRILTREAT™ (asupplemental oil wetting agent), available from Halriburton EnergyServices, Inc., Houston, Tex.; about 2 to about 6 pounds per barrelGELTONE™ (a viscosifier or suspending agent), available from HalliburtonEnergy Services, Inc., Houston, Tex.; and barite as needed for desiredfluid density.

[0018] An example formulation of a preferred spotting fluid of theinvention comprises, as the external phase, about 0.7 barrel (bbl) ofiso-butyl oleate as the external phase and, as the internal phase, about0.3 bbl of glycerin. This formulation is combined with about 8 lb/bbl ofEZ-MUL NTE™; about 1 lb/bbl of DRILTREAT™;about 3 lb/bbl of GELTONE II;and barite as needed for desired density.

[0019] The iso-butyl oleatelglycerin invert emulsion of the inventionhas the advantageous ability to not only lubricate the surfaces involvedin sticking of the metal (of drill pipe or other stuck equipment in thefilter cake) but also to dehydrate or destruct the filter cake forenhanced performance as a spotting fluid. The iso-butyl oleate oil phaseis effective at lubricating the surfaces and penetrating the filtercake. Glycerin is effective at dehydrating the filter cake. In fact,glycerin, with an a_(w)≅0.0 (a_(w) means activity, water phase), is evenbetter at such dehydration than is calcium chloride, with an a_(w)≅0.30,which has been known to be effective at dehydrating filter cakes.

[0020] The emulsions of the invention were tested for performance as aspotting fluid in a differential sticking tester, or STICKOMETER™,manufactured by and available from Halliburton in Houston, Tex. TheSTICKOMETER™ consists of a modified filtration cell in which a mud caketo be tested is deposited by filtration of a mud under pressure. A flatplate is pressed under load onto the mud cake. Spotting fluid is thenallowed to soak around the mud cake and stuck plate apparatus. After aperiod of time, typically about 16 hours, torque-to-flee is measured.This torque is a relative measure of sticking tendency. A typical testprocedure follows. Already prepared mud was allowed to filter under 500psi pressure, generating a mud cake, while collecting 10 ml of filtrate.The metal disk was then stuck in the mud cake, and 2 ml of additionalfiltrate was collected. For base mud, filtering was done overnightwithout collecting the 2 ml of filtrate. For spotting fluid evaluation,the pressure was relieved after 2 ml of filtrate, the base mud decanted,then spotting fluid loaded into the cell. Pressure was reapplied andfiltration continued overnight, for about 16 hours. The torque wasmeasured the next morning while maintaining 500 psi pressure on thecell.

[0021] In testing this invention, an invert-oil emulsion of iso-butyloleate and glycerine was prepared and tested in a STICKOMETER™ and testresults—torque to free in inch pounds (in/lbs)—and compared to resultswith other fluids, including known spotting fluids and commerciallyavailable spotting fluids such as COASTAL SPOT™, available from CoastalMud and Coastal Fluid Technologies, Lafayette, La., a division ofCoastal Chemical Co., LLC a Holland Chemical International Co. Tables1through 4 show the performance of various experimental and commercialspotting fluid treatments in selected mud systems. In each case, theisobutyl oleate/glycerine composition of the present invention yieldedequal or better results than any product tested. TABLE I Mud System/SpotTorque-to-Free (in/lbs) Base A (16 ppg Freshwater Lignosulfonate) 350Base A with addition of: Diesel oil 170 11.6 CaCl₂ brine 110 12.7 NaBrbrine 190 12.7 NaBr brine/3% TORQ TRIM II ™ 150 12.7 NaBr brine/3% FSEFluoro-surfactant 150 30% 12.7 NaBr brine/70% Glycerine 200 SqualaneC₃₀H₆₂ 120 Squalene C₃₀H₅₀ 180 Isobutyl Oleate Neat  60 Oleyl OleateNeat  80 16 ppg COASTAL SPOT ™/CaCl₂  50 16 ppg COASTAL SPOT ™/NaCl 17016 ppg Phase 1 of DUAL PHASE ™ 110 16 ppg Phase 1 & 2 of DUAL PHASE ™110 16 ppg Isobutyl Oleate/CaCl₂  70 16 ppg Isobutyl Oleate/Glycerine 40 16 ppg Oleyl Oleate/Glycerine  55

[0022] TORQ TRIM II™ is available from Halliburton Energy Services, Inc.in Houston, Tex.; COASTAL SPOT™ is available from Coastal Mud andCoastal Fluid Technologies in Lafayette, La.; and DUAL PHASE™ isavailable from Halliburton Energy Services, Inc. in Houston, Tex.

[0023] The base mud in Table 1 is a 16 lb/gal freshwater/lignosulfonatemud. This base mud shows torque-to-free at 350 inch-pounds, a “high”number in terms of sticking tendency, indicating the mud alone likelywill not be able to free a stuck pipe. A low torque-to-free numberrepresents or indicates low sticking tendency. As shown in Table 1, allof the various spotting fluid treatments provided some improvement overthe base mud for purposes of freeing stuck pipe. The isobutyloleate/glycerine system of the present invention yielded the bestperformance, with a very low torque-to-free number of 40. TABLE 2Torque-to-Free Mud System/Spot (in/lbs) Base B (16 ppg SeawaterLignosulfonate) 280 Base B with addition of: 16 ppg COASTAL SPOT ™/CaCl₂300 16 ppg ENVIRO-SPOT ™/Freshwater 270 16 ppg Phase 1 of DUAL PHASE ™290 16 ppg Phase 1 & 2 of DUAL PHASE ™ 290 16 ppg IsobutylOleate/Glycerine 210 16 ppg Isobutyl Oleate/Glycerine (after 250° F. hotroll) 180

[0024] COASTAL SPOT™ is available from Coastal Mud and Coastal FluidTechnologies in Lafayette, La.; ENVIRO-SPOT™ is available fromHalliburton Energy Services, Inc. in Houston, Tex.; and DUAL PHASE™ isavailable from Halliburton Energy Services, Inc. in Houston, Tex.

[0025] Table 2 shows results with a 16 lb/gal seawater/Iignosulfonatemud system. The control or base mud has a torqueto-free value of 280in/lbs. Best performance again was with the isobutyl oleate/glycerinecomposition of the present invention, providing a torque-to-free of 210in/lbs. Hot rolling this spotting fluid at 250° F. before conducting theSTICKOMETER™ test yielded further improved results. TABLE 3 MudSystem/Spot Torque-to-Free (in/lbs) Base C (16 ppg POLYNOX ™) 380 Base Cwith addition of: 16 ppg COASTAL SPOT ™/CaCl₂ 240 16 ppg Phase 1 of DUALPHASE ™ 260 16 ppg Isobutyl Oleate/Glycerine 160 Base D (16 ppg PHPAMud) 205 Base D with addition of: 16 ppg COASTAL SPOT ™/CaCl₂ 160 16 ppgPhase 1 of DUAL PHASE ™ 155 16 ppg Isobutyl Oleate/Glycerine 170

[0026] POLYNOX™ is available from Halliburton Energy Services, Inc. inHouston, Tex.; COASTAL SPOT™ is available from Coastal Mud and CoastalFluid Technologies in Lafayette, La.; and DUAL PHASE™ is available fromHalliburton Energy Services, Inc. in Houston, Tex.

[0027] Table 3 shows some limited results with a POLYNOX™ mud and with aPHPA (partially-hydrolyzed, polyacrylamide) based mud, both at 16lb/gal. Again, isobutyl oleate/glycerine of the present invention showedthe best results in the POLYNOX™ system. COASTAL SPOT™, DUAL PHASE™ andisobutyl oleate/glycerine of the present invention showed about the sameperformance in the PHPA mud system. TABLE 4 Mud System/SpotTorque-to-Free (in/lbs) Base E (12 ppg Freshwater Lignosulfonate) 185 Base E with addition of: 12 ppg DUAL PHASE ™ 115  12 ppg COASTALSPOT ™-old 75 12 ppg COASTAL SPOT ™-new 70 12 ppg IsobutylOleate/Glycerine 80

[0028] Table 4 shows results with a 12 lb/gal freshwater/lignosulfonatemud system. Three commercial products and the isobutyl oleate/glycerinecomposition of the present invention showed similar performance in thismud system. With each, torque was reduced by over 50%.

[0029] Further, the iso-butyl oleate/glycerin composition of the presentinvention is environmentally acceptable. Mysid shrimp LC₅₀ tests wereconducted according to industry standards. An invert emulsion comprisingthe oleate/glycerin composition was evaluated at 5 and 10 volume % ingeneric #7 drilling fluid (industry standard). Results for 96-hour LC50in mg/L SPP were 267,600 and 227,700 respectively. Gulf of Mexicominimum by regulation is 30,000. Operators prefer 100,000 or more.

[0030] Without wishing to limit the invention, it is expected that theisobutyl oleate/glycerine composition of the present invention would beused over a density range of about 10 to about 16 lb/gal., depending onthe circumstances of the case, and likely particularly associated withthe well and the stuck pipe. Table 5 shows rheology and mud propertiesfor an isobutyl oleateiglycerine invert mud system at 10, 13 and 16lb/gal densities. These values in Table 5 are consistent with a reliableand stable mud system over this density range. TABLE 5 Study of MudProperties or 10, 13, & 16 lb/gal experimental spotting fluid pillscomparison of GELTONE 11 & SUSPENTONE Sample Mark A A B B C C D D E E FF G** G** H*** H*** Experimental Spotting Fluid, 0.66* 0.62* 0.57* 0.66*0.62* 0.57* 0.57* bbl Glycerine, bbl 0.23 0.17 0.11 0.23 0.17 0.11 0.11SEE SEE Barite 124 293 456 123 293 456 456 B B GELTONE II ™, lb 4 3 2 —— — — E E SUSPENTONE ™, lb — — — 4 3 2 2 L L O O Density, lb/gal. 10.013.0 16.0 10.0 13.0 16.0 16.0 W W Stirred, min. 30 — 30 — 30 — 30 — 30 —30 — 30 — 30 — FANN 35: 80 120 80 120 80 120 80 120 80 120 80 120 80 12080 120 Temp ° F. 600 rpm 76 52 102 72 151 108 75 53 108 75 154 112 OFF290 O/S 170 300 rpm 45 30 59 41 85 60 46 31 64 43 88 63 S 180 212 91 200rpm 34 20 43 30 63 49 35 20 44 32 64 51 C 140 150 70 100 rpm 22 14 27 2039 28 20 15 28 22 40 30 A 95 85 40  6 rpm 6 4 7 5 9 7 6 4 7 6 9 8 L 3515 10  3 rpm 5 3 6 4 8 6 5 3 6 5 8 7 E 31 12 8 Plastic Viscosity, cp 3122 43 31 66 48 29 22 44 32 66 49 — 110 — 79 Yield Point, lb/100 sq. ft.14 8 16 10 19 12 17 9 20 11 22 14 — 70 — 12 10 sec gel, lb/100 sq. ft. 43 5 4 6 5 5 3 5 4 8 7 — 30 12 7 10 min gel, lb/10 sq. ft. 6 5 7 6 9 7 96 10 8 12 11 — 52 20 12 Electrical Stability, V 312 288 512 609 612 714504 512 761 832 1124 1180 1312 1406 395 412 Filtrate, 200° F., 500 psi,ml Oil, ml 27.4 36.4 17.2 Water, ml 8.8 14.6 0.8

[0031] The single asterisk in Table 5 designates values for theexperimental spotting fluid which comprised 8 lb EZ MUL NTE™ and 1 lbDRIL TREAT™ in a barrel of isobutyl oleate. Double asterisks in Table 5designates values for Experimental Spotting Fluid (Sample G) whichcomprised 8 lb EZ MUL NTE™ and 1 lb DRILTREAT™ in a barrel of oleyloleate. Triple asterisks in Table 5 designates values for Sample H whichcomprised COASTAL SPOT™ which comprised a 16.0 lb/gal pill mixedaccording to COASTAL SPOT™ guidelines.

[0032] Table 6 shows a decided advantage of the invention. The testresults of Table 6 show not only the effectiveness of theoleate/glycerin invert emulsion as a spotting fluid, but also that suchspotting fluid in the water-based drilling fluid does not have to beseparated and removed from the operating mud system after use, savingtime and money. Spotting fluid volumes are typically about 50 to about100 barrel “pills” in operating mud systems of about 1000 barrels ormore. Once stuck pipe is no longer stuck, i.e., is free, the spottingfluid composition of the present invention used to free the pipe can becirculated in with the operating mud system. Table 6 shows that up toabout 10 volume percent of isobutyl oleate/glycerine fluid mixed in witha seawater/lignosulfonate mud creates no final mud problems. To thecontrary, the lubricity of the final mud mixture is improved some byleaving in the isobutyl oleate/glycerine, a further advantage of theinvention. TABLE 6 CONTAMINATION TESTS (sea water mud) InitialProperties and Properties After Hot Rolling at 150° F. and 250° F.Sample Mark A A B B C C AA D D DD Base Mud*, bbl 1.0 1.0 1.0 1.0 1.0 1.01.0 1.0 1.0 1.0 Experimental — — 0.05 0.05 0.10 0.10 — 0.10 0.10 0.10Spotting Fluid Pill, bbl Q-BROXIN ™, lb — — — — — — — 2.0 2.0 2.0CARBONOX ™, lb — — — — — — — 2.0 0.0 1.0 Caustic soda, lb 1.0 1.0 1.0Stirred, min 15 15 15 15 15 15 15 15 15 15 Rolled at 150° F., hr 0 16 016 0 16 16 0 16 16 Rolled at 250° F., hr — — — — — — 16 — — 16 TestTemp., ° F. 80 80 80 80 80 80 80 80 80 80 Mud Density, 16.0 16.0 16.016.0 16.0 16.0 16.0 16.0 16.0 16.0 lb/gal. Plastic Viscosity, 40 44 3438 39 38 37 35 41 39 cp Yield Point, lb/100 18 13 36 31 41 36 13 25 1913 sq. ft 10 sec gel, lb/100 7 6 16 12 20 17 4 8 7 5 sq ft 10 min gel,lb/100 21 18 40 30 50 41 12 24 18 15 sq ft pH 9.7 9.4 9.8 9.5 9.7 9.28.9 11.7 11.2 9.2 API Filtrate, ml — 2.6 — 3.2 — 3.6 — — 3.0 — Filtrate,250° F., 500 — 8.4 — 10.0 — 9.8 — — 8.2 — psi, ml FANN 35: 600 rpm 98101 104 107 119 112 87 95 101 91 300 rpm 58 57 70 69 80 74 50 60 60 52200 rpm 45 43 55 57 65 63 38 50 48 44 100 rpm 30 27 37 38 48 45 21 30 2822  6 rpm 9 7 18 14 24 19 5 9 8 6  3 rpm 7 6 16 12 22 17 4 8 7 5LUBRICITY — 0.23 — — — — — — 0.18 — COEFFICIENT % Lubricity — — — — — —— — 21.7 Improvement

[0033] The Base Mud in Table 6 is comprised of 0.72 bbl sea water, 12 lbAQUAGEL™, 30 lb Rev Dust, 4 lb Q-BROXIN™, 1 lb caustic soda, 416 lbbarite and 0.5 lb BARAZAN PLUS™. AQUAGEL™ is available from HalliburtonEnergy Services, Inc. in Houston, Tex.; Q-BROXIN™ is available fromHalliburton Energy Services, Inc. in Houston, Tex.; and BARAZAN PLUS™ isavailable from Halliburton Energy Services, Inc. in Houston, Tex.

[0034] In the method of the invention, a spotting fluid comprising aninvert water-in-oil emulsion of the invention—glycerin or calciumchloride brine in isobutyl oleate—is used to free stuck pipe,particularly differentially stuck pipe.

[0035] The foregoing description of the invention is intended to be adescription of preferred embodiments. Various changes in the details ofthe described composition and method can be made without departing fromthe intended scope of this inventions as defined by the appended claims.

We claim:
 1. A method for freeing differential stuck pipe in asubterranean well-drilling operation with water based drilling fluids,said method comprising: (a) determining the density needed for aspotting fluid to facilitate positioning of said spotting fluid at thesite of the sticking; (b) preparing or obtaining a spotting fluidcomprising a water-in-oil invert emulsion comprising iso-butyl oleate asthe external phase and glycerin as the internal phase; (c) adjusting thedensity of said spotting fluid with additives such that the neededdensity may be obtained; (d) introducing the spotting fluid into thewellbore; (e) allowing said spotting fluid to reach the location of thestuck pipe and to unstick the stick pipe; and (f) resuming drillingoperation without removing the spotting fluid from the well.
 2. Themethod of claim 1 wherein said additives comprise barite.
 3. The methodof claim 1 wherein said spotting fluid contacts the surface of said pipeand the wall of said well at the sticking point in unsticking said pipe.4. The method of claim 1 further comprising allowing said spotting fluidto mix with drilling fluid used in the drilling operation.
 5. The methodof claim 4 wherein said spotting fluid enhances the lubricity of saiddrilling operation.
 6. A method for freeing differential stuck pipe in asubterranean well drilling operation with water based drilling fluids,said method comprising: (a) determining the density needed for aspotting fluid to facilitate positioning of said spotting fluid at thesite of the sticking; (b) preparing or obtaining a spotting fluidcomprising a water-in-oil invert emulsion comprising iso-butyl oleate asthe external phase and calcium chloride as the internal phase; (c)adjusting the density of said spotting fluid with additives such thatthe needed density may be obtained; (d) introducing the spotting fluidinto the wellbore; (e) allowing said spotting fluid to reach thelocation of the stuck pipe and to unstick the stick pipe; and (f)resuming drilling operation without removing the spotting fluid from thewell.
 7. The method of claim 1 wherein said additives comprise barite.8. The method of claim 1 wherein said spotting fluid contacts thesurface of said pipe and the wall of said well at the sticking point inunsticking said pipe.
 9. The method of claim 1 further comprisingallowing said spotting fluid to mix with drilling fluid used in thedrilling operation.
 10. The method of claim 4 wherein said spottingfluid enhances the lubricity of said drilling operation.
 11. A spottingfluid for freeing differential stuck pipe comprising an invertwater-in-oil emulsion comprising iso-butyl oleate as the external phaseand glycerin as the internal phase.
 12. A spotting fluid for freeingdifferential stuck pipe comprising an invert water-in-oil emulsioncomprising iso-butyl oleate as the external phase and calcium chlorideas the internal phase.
 13. A method for freeing stuck pipes in -asubterranean welldrilling operation comprising introducing a spottingfluid having the composition of claim 11 into the interior of a drillpipe, forcing said fluid through the drill bit and allowing said fluidto contact the exterior of the pipe and the wall of the well at thepoint of sticking.
 14. A method for freeing stuck pipe in a subterraneanwell-drilling operation comprising introducing a spotting fluid havingthe composition of claim 12 into the interior of a drill pipe, forcingsaid fluid though the drill bit and allowing said fluid to contact theexterior of the pipe and the wall of the well as at the point ofsticking.